You’d better believe that cost, however small, is passed along to the clients of those law firms.
Now if that cost were to go to zero- no I don’t think the lawyers will charge less. But I do think that even the presence of a paywall reinforces the perceived scarcity of the legal profession. My thought is that if these documents were available more freely, we would see more democratization of the legal system.
For example, small claims doesn’t require legal representation. But knowing previous case law could definitely help even a lay person prepare a case.